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1 


CTir 


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THE  CONNECTICUT 


AGRICULTURAL   EXPERIMENT 
STATION 


NEW  HAVEN,  CONN. 


BULLETIN   188,  SEPTEMBER,   1915 


FURTHER  EXPERIMENTS  ON 
INHERITANCE  IN  MAIZE 


BY 

H.  K.  HAYES  and  E.  M.  EAST. 


CONNECTICUT 
AGRICULTURAL  EXPERIMENT  STATION. 

OFFICERS  AND  STAFF. 


BOARD  OF  CONTROL 

His  Excellenc}^   Marcus   H.   Holcomb,   e.v-officio,  President. 

Prof.  H.  W.  Conn,  Vice  President  Middletown 

George  A.  Hopson,  Secretary   Wallingford 

E.  H.  Jenkins,  Director  and  Treasurer   New  Haven 

Joseph  W.  Alsop   Avon 

Wilson   H.   Lee    Orange 

Frank  H.   Stadtmueller    Elmwood 

James  H.  Webb Hamden 


Administration,  E.    H.   Jenkins,    Ph.D.,   Director  and   Treasurer. 

'  Miss   V.   E.   Cole,   Libra:  ian    and   Stenographer. 

Miss  L.  M.  Brautlecht,  Boolxkeeper  and  Stenographer. 
William  Veitch^  In  charge  of  Buildings  and  Grounds. 

Chemistry. 

Analytical   Laboratory.    John    Phillips    Street,    M.S.-,    Chemist   in    Charge. 
E.  Monroe  Bailey,  Ph.D.,  C.  B.  Morison,  B.S. 
C.    E.    Shepard.    G.    L.    Davis.    Assistants. 
Hugo    Lange,    Laboratory   Helper. 
V.    L.    Churchill,    Sampling   Agent. 
Miss    E.    B.    Whittlesey^    Stenographer. 


Proteid  Researcli. 


T.    B.    Osborne,    Ph.D.,    D.Sc,    Chemist   in    Charge. 
Miss   E.    L.    Ferry,    M.S.,   Assistant. 


Botanv. 


G.  P.   Clinton,  Sc.D.,  Botanist. 
E.    M.    Stoddard,   B.S.,   Assistant  Botanist. 
Miss   E.    B.    Whittlesey,    Herbarium   Assistant. 
G.    E.   Grah.^m,   General  Assistant. 


Entomology. 


W.  E.  Britton,  Ph.D.,  Entomologist ;  State  Ejitomologist. 
B.    H.   Walden,    B.Agr.,   First  Assistant. 
Q.   S.   LowRY,    B.Sc,   I.   W.   Davis,  B.Sc.  * 
M.   p.   Zappe,   B.S.  ' 

Miss    G.    A.    Foote,    Stenographer. 


.4ssistants. 


Forestry. 


Walter     O.     Filley,    Forester;    also    State    Forester 

and  State  Forest  Fire  Warden. 
A.  E.  Moss.  J\I.F.,  Assistant  State  and  Station  Forester. 
Miss    E.    L.    jXverv.    Stenographer. 


Plant  Breeding. 


Donald    F.    Jones,    B.S.,    Plant   Breeder. 
C.    D.    Hubbell,    Assistant. 


Vegetable   Growing 


Howard   F.    FIuder,    B.S. 


FURTHER    EXPERIMENTS    ON    INHERITANCE    IN 

MAIZE. 

BY 

H.  K.  Hayes  *  and  E.  M.  East. 

This  paper  is  a  report  on  the  inheritance  of  certain  differ- 
ences in  the  endosperm  of  various  maize  races  that  have  been 
made  the  basis  of  a  division  into  the  subspecies  cverta,  indurata. 
indentata  and  amylacea.  To  these  investigations,  a  genetic 
study  of  the  shape  of  seed  which  characterizes  the  socaUed 
rice  pop  corns   is  added. 

The  writers  take  pleasure  in  acknowledging  the  efficient 
aid  of  Mr.  A.  F.  Schultze,  assistant  botanist  at  the  Connecticut 
Agricultural  College,  and  Mr.  C.  D.  Hubbell,  assistant  at  the 
Connecticut  Agricultural  Experiment  Station,  in  the  consider- 
able amount  of   field  work   involved. 

MATERIAL   AND   METHODS. 

The  parental  races  used  in  the  crosses  were  self-fertilized 
for  several  years  before  any  hybrids  were  made,  and  are  be- 
lieved to  have  been  homozygous  for  the  characters  studied. 
The  material  from  which  these  races  originated  was  described 
in  a  previous  publication  (See  East  and  Hayes,  1911),  bui 
the    following  additional   points   regarding   it   should   be   noted ; 

1.     Zea  mays  evcrta.     The  pop  corns. 
No.    64.     White   rice   pop. 

This  white  pop  is  one  of  the  lines  which  has  been  pro- 
duced from  No.  23,  (East  &  Hayes,  1911).  It  breeds  true 
to   the   "rice"   type   of   seed, — sharply   pointed   where   the   style 


*  Mr.  Hayes  resigned  January  1,  1914,  to  take  charge  of  plant 
breeding  work  in  the  Experiment  Station  and  College  of  Agriculture  of 
the  University  of  Minnesota.  The  experimental  work  here  reported  was 
carried  on  at  the  Connecticut  Station  as  an  Adams  Fund  Project.  The 
Minnesota  Experiment  Station  and  the  Bussey  Institution  of  Harvard, 
should  be  given  credit  for  time  spent  in  the  preparation  of  this  paper  for 
publication. 


2  CONNECTICUT    EXPERIMENT     STATION,    BULLETIN     188. 

(silk)  was  attached, — although  there  is  some  variation  in  the 
degree  to  which  this  character  is  expressed.  The  seeds  con- 
tain only  very  small  amounts  of  soft  starch. 
No.  65.  A  white,  flint-like  pop. 
This  is  a  strain  produced  from  No.  26,  of  our  previous 
publication.  Its  seeds  resemble  those  of  a  typical  flint  variety 
in  shape,  and  contain  only  very  small  amounts  of  soft  starch. 

2.  Zea  mays  indurata.     The  flint  corns. 

No.  5.  Watson's  white  flint. 
This  variety  is  a  true  white  flint  which  developes  a  red 
pericarp  in  full  sunlight.  The  depth  of  tint  which  developes 
naturally  is  therefore  inversely  proportional  to  the  thickness  of 
the  husk.  The  seeds  contain  a  larger  proportion  of  corneous 
starch  than  many  races  of  flint  corn,  though  less  than  that  shown 
by  the  two  pop  varieties  just  described.  As  in  all  flints,  how- 
ever, there  is  a  small  zone  of  soft  starch  in  the  center  of  the  seed. 

3.  Zea  mays  indentata.     The  dent  corns. 

No.   6.     Learning  dent. 
This  is  a  vigorous  strain  of  a  famous  yellow  dent.     Like 
all  varieties  of  its  group,  the  soft  starch  extends  over  the  whole 
summit  of  the  seeds,  yet  the  layer  is  thin  enough  to  allow  the 
race  to  be  classified  as  a  smooth  dent  (i.  e.  not  beaked). 

4.  Zea  mays  amylacea.     The  flour  corns. 

No.  10.  White  flour. 
This  is  a  floury  race  with  seeds  resembling  the  average  8 
rowed  flint  in  shape.  Though  the  seeds  usually  contain  only 
floury  starch,  sometimes  an  almost  imperceptible  layer  of  corn- 
eous starch  developes  in  the  exterior  of  the  endosperm.  It 
seems  likely  that  this  variation  is  an  efifect  of  external  condi- 
tions  rather  than  of  gametic  impurity. 

The  plantings  have  always  been  made  from  the  original 
seed  envelope,  and  pains  have  been  taken  to  prevent  the  mis- 
placement of  seeds. 

The  different  families  were  marked  in  the  field  by  heavy 
stakes  to  which  wired  tree  labels  were  attached,  but  to  prevent 
error  through  their  misplacement  a  planting  plan  was  made  each 
year  showing  the  exact  location  and  the  number  of  hills  of  each 
strain. 


INHERITANCE   IN    MAIZE.  3 

Classification  of  seeds  was  made  only  from  hand  pollinated 
ears,  although  the  remaining  ears  of  a  selection  were  always 
examined,  and  in  the  case  of  those  seed  characters  not  immediate- 
ly affected  by  pollination,  were  used  in  determining  the  range 
of  variation. 

The  various  races  were  given  different  numbers  as  No.  10 
flour  corn  and  No.  5  flint  corn.  A  cross  between  10  and  5  was 
then  written  as  10  x  5  the  female  parent  appearing  first.  Differ- 
ent self-pollinated  ears  obtained  from  grov\^ing  the  cross  between 
(10x5)  were  labeled  (10x5)-l,  (10  x  5)-2,  etc.  Later  genera- 
tions were  labeled  as  (10x5) -1-2,  (10x5) -1-3,  (10x5)-2-4,  etc. 
If  the  F^  generation  was  pollinated  with  pollen  from  the  flint 
parent,  this  ear  received  the  label  (10x5)-l  x  (5-2)-8-3,  as  the 
case  might  be.  This  back  cross  was  planted  the  following  year 
as  (10x5  x5).  Thus  we  had  complete  records  of  the  parents 
and  ancestry  of  our  various  lines. 

The  field  technique  has  been  described  in  previous  publica- 
tions. 

For  convenience  the  various  crosses  Avill  be  considered  under 
special  headings. 

Family    (10x5),   Flour  x   Flint. 

A  cross  between  the  floury  race  No.  10  and  flint  race  No.  5 
was  made  in  1910,  the  resulting  seeds  resembling  the  female 
parent.  As  indicated  above,  the  characteristic  difference  between 
these  races  is  the  amount  of  soft  starch  in  the  seeds.  The  flint 
race  produces  a  small  quantity  of  soft  starch  in  the  center  of  the 
seed,  surrounded  b}^  a  large  layer  of  corneous  starch,  while  the 
flour  race  produces  only  an  occasional  trace  of  corneous  starch 
around  the  exterior  of  the  endosperm.  No  immediate  effect  of 
pollination  through  double  fertilization  was  expected,  as  both 
our  own  earlier  results  and  those  of  other  investigators  (Correns 
and  Lock)  were  thought  to  imply  that  these  differences  in  the 
starchy  character  of  the  endosperm  behaved  in  heredity  as  if 
they  pertained  to  the  plant  rather  than  to  the  endosperm.  On 
growing  this  cross  in  1910,  however,  we  were  much  surprised 
to  find  a  clear  segregation  of  seeds  on  each  ear.  This  fact 
showed  that  the  physical  condition  of  the  starch  in  these  races 


4  CONNECTICUT     EXPERIMENT     STATION,     BULLETIN     188. 

was  not  a  maternal  character,  since  in  that  case  we  should  have 
expected  a  uniform  population  of  seeds  on  the  F^^  ears,  resembling 
either  the  male  or  female  parents  or  intermediate  between  them. 
A  classification  of  the  seeds  from  the  ears  of  .the  F^  gen- 
eration plants,  is  given  in  Table  1.  Only  two  classes  could  be 
made :  corneous  seeds  like  the  flint  parent,  and  floury  seeds  re- 
sembling the  floury  parent.  There  was  no  difiicvilty  in  dividing 
the  seeds  into  these  two  classes.  Of  the  thirteen  ears  shown 
in  Table  1,  some  contained  a  greater  proportion  of  flint  or  of 
floury  seeds  than  others,  but  all  gave  close  approximations  to  a 
1  to  1  ratio.  This  being  a  novel  F^  ratio,  further  experiments 
were  made  to  find  a  genetic  interpretation  of  it. 

TABLE  1. 

Self-pollinated  Ears  from  the  F^  Generation  of  a  Cross 
Between  No.  10  Flour  and  No.  5  Corneous  Flint. 


Ear  Number 

Corneous  Seeds 

Floury  Seeds 

(10  X  5)-l 

145 

186 

-3 

208 

142 

-4 

169 

161 

-5 

156 

169 

-6 

181 

166 

-7 

189 

172 

-8 

175 

203 

-9 

168 

165 

-10 

213 

213 

-11 

209 

205 

-12 

238 

237 

-13 

190 

197 

-14 

252 

223 

Total 

2493 

2439 

The  floury  seeds  of  (TOxo)-T  and  (10x5)-8  were  labeled 
(10x5)-TS  and  (10x5)-8S  to  distinguish  them  from  the  cor- 
neous (flint-like)  seeds  of  the  same  ears,  which  were  labeled 
(10x5)-7C  and  (10x5)-8C  respectively.     The  data  from  sev- 


^  The  word  hybrid  in  these  discussions  is  used  in  a  peculiar  sense  to 
avoid  longer  descriptions.  It  means  a  cob  bearing  a  population  of  seeds 
belonging  to  more  than  one  phenotype. 


INHERITANCE    IN    MAIZE.  0 

eral  self-fertilized  ears  obtained  by  growing  the  flotny  seeds 
are  given  in  Table  2.  Of  a  total  of  11  hand-pollinated  ears,  8 
were  hybrid',  and  gave  1  to  1  ratios  with  a  total  of  748 
corneous  to  691  floury  seeds.  The  other  3  ears  bred  true  for 
the  floury  habit. 

Of  the  open  field  or  naturally  pollinated  ears,  28  were  hy- 
brids and  23  pure  floury.  This  gives  a  total  of  36  hybrids  to 
26  pure  floury,  which,  considering  the  number  grown,  is  a  rea- 
sonable approximation  of  a  1  to  1  ratio. 

TABLE   2. 

Self-pollinated  Ears  Obtained  Through  Growing  Floury 

Seeds  of  Ears   (10  x  5) -7  and   (TO  x  5) -8. 


Ear 

Number 

Corneous 

Seeds 

Floury    Seeds 

(10  X 

5) -7  S-1 

108 

125 

" 

-7  S-2 

76 

59 

" 

-7  S-4 

162 

126 

" 

-7  S-7 

58 

55 

" 

-8  S-5 

100 

97 

" 

-8   S-6 

53 

48 

" 

-8  S-7 

91 

89 

" 

-8  S-8 

100 

92 

" 

-8  S-2 

Pure  Floury 

" 

-8  S-3 

"             " 

" 

-8  S-4 

.(             <( 

Total  in 

hybrid  ears 

748 

691 

Table  3  gives  the  results  of  planting  the  corneous  seeds  of 
ears  (10x5)-r  and  (10x5)-8.  Of  a  total  of  9  self-fertilized 
ears,  5  proved  to  be  hybrids  and  4  were  pure  corneous.  The 
ratio  of  corneous  to  floury  seeds  in  these  5  hybrid  ears  was 
464  corneous  to  482  floury,  a  close  approximation  of  1  to  1. 
Of-  the  open  field  ears  38  were  corneous  and  34  hybrids.  Thus 
in  this  case  the  hybrid  and  the  pure  corneous  ears  are  clearly 
in  a  1  to  1  ratio. 


6  CONNECTICUT    EXPERIMENT    STATION,     BULLETIN     188. 

TABLE  3. 

Self-pollinated  Ears  Obtained  Through  Growing  Corneous 

Seeds  of  Ears  (10  x  5)-7  and  (10  x  5)-8. 


.    Ear  Number 

Corneous   Seeds 

Floury   Seeds 

(10  X  5)-7C-6 
-7C-9 
-SC-3 
-8C-8 
-8C-10 

30 

73 

97 

191 

73 

29 
101 

81 

211 

60 

-7C-5 
-7C-8 
-8C-5 
-8C-6 

Pure  corneous 

Total  in  hybrid  ears 

464 

482 

Table  -l  gives  the  results  of  pollinating  ears  of  the  F^  plants 
with  pollen  from  the  parental  strains  No.  10  flour,  and  No.  5 
flint,  respectively.  Only  1  ear  was  obtained  from  the  back 
cross  between  (10x5)  and  the  No.  10  parent.  This  ear  had 
156  corneous  and  184  floury  seeds.  Three  ears  resulted  from 
crossing  plants  of  (10  x  5)  with  the  flint,  or  No.  5  parent.  These 
ears  showed  various  ratios  of  corneous  to  floury  seeds,  but  the 
deviations  from  1 :  1  ratios  were  not  all  in  the  same  direction. 
Of  the  total  number  of  seeds  in  the  four  ears,  541:  were  corneous 
and  543  floury. 


TABLE  4. 

Ears  of  the  First  Generation  Cross  of  (10  x  5)  Pollinated 

With  Pollen  From  the  Pure  Parents,  No.  10  Flour 

AND  No.  5  Corneous  Flint. 


Ear    Number 

Corneous  Seeds 

Floury   Seeds 

(10  X  5) -13  X   (10-3) -14 

-  3  X   (  5-3) -1 

-  1  X   (  5-3) -3 

-  5  X   (-5-3) -7 

156 
102 
107 
179 

184 
79 
79 

201 

Total 

544 

543 

INHERITANCE   IN    MAIZE.  7 

Table  5  gives  the  results  obtained  from  planting  floury  seeds 
of  ears  (10  x  5)-5  x  (5-3)-7  and  (10  x  5)-l  x  (5-3)-3  of  Table 
4.  It  was  expected  that  such  seeds  would  be  hybrids  between 
the  corneous  and  floury  types  and  should  therefore  give  hybrid 
ratios  when  grown.  The  table  shows  10  self-pollinated  ears  which 
gave  a  ratio  of  1014  corneous  to  850  floury  seeds.  Seventy- 
nine  naturally  pollinated  ears  were  all  hybrids  showing  a  definite 
segregation.  The  corneous  seeds  of  ears  (10  x  5) -5  x  (5-3) -7 
and  (10x5)-l  x  (5-3)-3  were  also  tested.  A  total  of  13  self- 
fertilized  and  87  open  field  ears  were  pure  corneous  flints  like 
the  corneous  flint  parent,  No.  5. 

TABLE  5. 

Self-pollinated    Ears    Obtained    From    Planting    Floury 

Seeds  of  Ear  (10  x  5) -5  x  (5-3) -7  and  Ear 

(10  X  5)-l  X  (5-3)-3. 


Ear  Number 

Co 

rneous  Seeds 

Floury  Seeds 

(10  X  5)  X  5-7S-6 

102 

116 

-5 

125 

137 

-1 

77 

48 

-8 

126 

110 

"          -2 

,  128 

106 

-7 

67 

36 

(10  X  5)  X  5-3S-2 

93 

58 

-8 

74 

71 

-1 

126 

92 

-6 

96 

76 

Total 

1014 

850 

Table  6  gives  the  results  obtained  from  planting  corneous 
seeds  of  ears  (10x5)-13  x  (10-3)-14.  As  these  seeds  were  as- 
sumed to  be  the  result  of  a  cross  between  corneous  and  floury 
types,  it  was  to  be  expected  that  all  resulting  ears  would  show 
segregation.  Five  self-fertilized  ears  evidently  came  from  hybrid 
seeds  as  they  gave  a  total  ratio  of  653  corneous  to  620  floury 
seeds.  Of  57  open  field  ears,  56  came  fromi  hybrid  seeds.  One 
ear  which  was  somewhat  immature  probably  was  a  pure  soft 
floury  ear.  This  result  may  be  explained  by  assuming  that  one 
floury  seed  was  planted  by  mistake. 


8  CONNECTICUT    EXPERIMENT     STATION,    BULLETIN     188. 

Of  the  7  self-fertilized  ears  obtained  from  planting  the  floury 
seeds  of  the  cross  between  (10x5)-13  x  (10-3)-14,  all  were 
pure  floury.  Of  the  open  pollinated  ears,  11  were  unquestion- 
ably pure  floury  while  2  indicated  segregation.  These  ears  may 
have  come  from  corneous  seeds  planted  by  mistake,  althougn 
it  is  possible  that  a  few  stalks  Avere  mislabeled  at  harvesting 
time,  as  the  stalks  bearing  the  open  pollinated  ears  all  were 
shocked  on  the   same   field. 


TABLE  6. 

Self-pollinated   Ears   Obtained   From    Planting   Corneous 
Seeds  of  Ear  No.  (10  x  5) -13  x  (10-3) -14. 


Ear  Number 

Corneous   Seeds 

Floury  Seeds 

(10x5)  X10-3-14C-4 

137 

116 

-9 

200 

172 

_7 

70 

71 

-6 

73 

94 

-10 

183 

167 

Total 

653 

620 

Table  7,  gives  the  results  of  planting  seeds  of  Ear  No. 
(5-3) -20,  pure  corneous  flint,  which  was  pollinated  with  pollen 
from  F-L  generation  cross  (10  x  5).  There  was  no  immediate 
efl:'ect  of  the  pollen  of  (10  x  5)-6  upon  the  pure  flint  ear  (5-3) -20. 
Of  5  self-fertilized  ears  obtained  from  growing  this  cross,  -1 
showed  segregation,  giving  a  total  of  528  corneous  to  508  floury 
seeds,  and  1  was  pure  corneous.  Of  the  open  field  ears  24  were 
pure  corneous  and  34  showed  segregation.  These  results  show 
that  the  pollen  grains  carry  the  factors  for  corneous  and  floury 
starch  in  the  ratio  of  1  to  1. 

Table  8  gives  the  results  of  planting  seeds  of  ear  (10-3) -13, 
which  was  pollinated  with  pollen  from  an  F^  ear  (10  x  5) -14. 
There  was  no  visible  efitect  on  the  endosperm  of  (10-3)-13  due 
to  crossing.  Three  of  the  self-fertilized  ears  obtained  from  this 
cross  had  a  total  of  397  corneous  to  377  floury  seeds;  6  self- 
fertilized  ears  were  like  the  floury  parent.  Of  the  open  field 
ears,  32  were  homoz3'gous  floury  and  30  were  hybrids. 


INHERITANCE    IN    MAIZE. 


y 


TABLE  7 

Self-pollinated   Ears   Obtained   From    Planting   Corneous 
Seeds  of  Ear  No.  (5-;3)-20  x  (10  x  5)-6. 


Ear  Number 

Corneous   Seeds 

Floury   Seeds 

5  X   (10  X  5) -2 
-3 
-5 
-S 
-9 

116 
116 
126 
170 
Pure    corneous 

113 
116 
120 

159 

Total  in  hybrid  ears 

528 

508 

TABLE  8. 

Self-pollinated  Ears  Obtained  From  Planting  Floury 
Seeds  of  Ear  No.  (10-3) -13  x  ( 10  x  5) -11. 


Ear    Number 

Corneous   Seeds 

Floury   Seeds 

10  X    (10  X  5)-6 

158 

156 

-7 

84 

79 

-4 

155 

142 

-1 

Pure   floury 

-3 

-4 

.-5 

-6 

Total  in  hybrid  ears 

397 

377 

Table  9  gives  the  results  of  planting  the  corneous  seeds  of 
( 10  X  5  )-8C-8  and  ( 10  x  5)-8S-8.  This  F3  generation  was  grown 
to  determine  whether  a  constant  splitting  into  a  1  to  1  ratio  in 
the  hybrid  ears  could  be  expected.  The  results  show  no  great 
deviations  from  this  ratio.  On  9  selfed  ears  showing  segrega- 
tion there  were  996   corneous  and  951  floury  seeds. 

The  total  progeny  of  (10x5)-8C-8  consisted  of  12  hybrid 
ears  and  15  corneous  ears,  while  the  progeny  of  (10x5)-8S-8C 
included  17  hybrid  and  10  pure  corneous  ears.  Considering 
the  few  individuals  grown  the  data  corroborate  those  of  the  pre- 
vious generation. 


10  CONNECTICUT    EXPERIMENT     STATION,     BULLETIN     18S. 


TABLE  9. 

Self-pollinated   Ears   Obtained   From    Planting   Corneous 

Seeds  of  F,  Generation  Ears  (10  x  5)-8C-8  and 

(10  X  5)-8S-8. 


Ear    Number 

Corneous   Seeds 

Floury   Seeds 

(10  X  5)-8C-8C-l 

150 

116 

-3 

116 

133 

-2 

Pure 

corneous 

-5 

11 

_7 

" 

-8 

" 

(10  X  5)-SS-8C-l 

114 

132 

-2 

96 

115 

-4 

103 

98 

-5 

142 

104 

-6 

114 

95 

-7 

89 

101 

-8 

72 

60 

-3 

Pure 

corneous 

Total  in  hybrid  ears 

996 

954 

Table  10  gives  the  results  of  planting  floury  seeds  of  ears 
(10  X  5)-8C-8  and  (10  x  5)-8S-8.  '  In  8  self-pollinated  ears  there 
were  a  total  of  966  corneous  and  997  floury  seeds.  Among  the 
progeny  of  (10  x  5)-8C-8S  there  were  17  segregating  ears  and  16 
floury  ears,  while  the  progeny  of  (10  x  5)-8S-8S  gave  a  total  of 
12  segregating  and  10  floury  ears.  The  data  in  these  two  tables 
show  that  the  progeny  of  an  ear  which  is  a  cross  between  floury 
and  corneous  may  be  expected  to  give  a  ratio  in  Fo  of  1  cor- 
neous, 2  segregating  to  1  floury  ear. 


INHERITANCE    IN    MAIZE,    SUMMARY. 


.11 


TABLE  10. 

Self-pollinated  Ears  Obtained  From  Planting  Floury  Seeds 
OF   (10  X  5)-8C-8  AND   (10  X  5)-8S-8. 


Ear  Number 

Corneous  Seeds 

Floury  Seeds 

(10  X  5)-SC-SS-l 

113 

132 

-2 

157 

174 

-5 

155 

150 

-6 

100 

98 

-7 

150 

150 

(10  :;  5)-8S-8S-2 

98 

107 

-3 

96 

100 

-4 

98 

86 

-1 

-4 

(10  X  5)-8C-8S-8 

-3 

Pure  Floury 

(I 

Total  in  hybrid  ears 

•966 

997 

To  test  the  purity  of  apparently  homozygous  segregates  the 
seeds  of  pure  corneous  ear  (10  x  5)-8C-6  were  planted.  A  total 
of  63  ears  were  all  pure  for  the  corneous  habit.  Pure  floury 
ear  (10x5)-8S-3  gave  a  progeny  of  78  ears.  All  were  of  a 
similar  character  and  contained  seeds  which  were  nearly  filled 
with  soft  starch.  There  were  traces  of  corneous  matter  in  some 
seeds,  but  under  Connecticut  conditions  the  floury  parent  also 
produces  traces  of  corneous  matter  in  a  few  seeds. 


Summary  and  Interpretation  of  Results. 

In  general,  no  matter  which  variety  was  used  as  the  female 
parent,  there  was  no  immediate  visible  efl:ect  of  the  male  parent 
in  the  endosperm  of  crosses  between  No.  5  flint  and  No.  10 
floury  maize.  The  F^  generation  plants  produced  ears  in  which 
there  was  a  clear  segregation  of  corneous  and  floury  seeds  in 
a  1  to  1  ratio.  This  ratio  was  unaffected  whether  the  F^  ears 
were  pollinated  with  pollen  from  either  the  pure  flint  or  the  pure 
floury  parent.  The  progeny  of  a  cross  between  F^  and  the  flint 
parent  gave  a  ratio  of  1  hybrid  ear  to  1  pure  flint  ear.  Like- 
wise the  progeny  of  a  cross  between  F,^  and  the  floury  parent 
gave    a    ratio    of    1    floury    ear   to    1    hybrid  ear.       Seventy-six 


12  CONNECTICUT    EXPERIMENT    STATION,     BULLETIN     188. 

Fo  ears  produced  from  a  self -fertilized  F^  ear  of  cross  (10  x  5), 
gave  a  ratio  of  1  pure  flint  ear,  2  hybrid  ears  and  1  pure 
floury  ear.  The  flint  and  the  floury  ears  bred  true  in  later 
generations. 

A  total  of  69  self-fertilized  ears  showing  segregation  gave 
a  ratio  of  8,803  corneous  seeds  to  8,562  floury  seeds.  This  is 
a  ratio  of  1  to  .961  or  approximately  1  to  1. 

The  above  results  prove  that  the  visible  endosperm  character 
of  a  seed  shows  the  potentiality  of  the  female  gamete  which 
entered  into  that  particular  seed,  and  that  the  male  gametes 
have  no  immediate  effect  on  the  endosperm  to  determine  whether 
they  be  corneous  or  floury.  Data  from  later  generations,  how- 
ever, show  that  the  pollen  grains  of  plants  from  hybrid  seeds 
transmit  both  the  corneous  and  the  floury  condition,  approxi- 
mately yi  carrying  a  factor  for  corneous  seeds  and  the  other 
half  a  factor  for  floury  seeds. 

Two  hypotheses,  will  explain  the  facts :  either  there  is  no 
fusion  between  the  female  endosperm  nucleus  and  the  so-called 
second  male  nucleus  of  the  pollen  grain,  in  which  case  the  en- 
dosperm developes  wholly  from  the  endosperm  nucleus  of  the 
embryo  sac  and  therefore  exhibits  the  gametic  character  of  the 
egg  cell ;  or,  there  is  dominance  of  the  condition  of  the  mother. 
As  ordinarily  two  female  polar  nuclei  unite  with  a  single  male 
nucleus  to  produce  the  endosperm  it  might  be  expected  that  this 
double  dose  of  the  female  character  should  predominate  over  a 
single  dose  of  the  male  character,  so  that  by  inspection  the  seeds 
would  be  classed  as  of  the  mother  type.  Correns  (1901)  used  the 
second  hypothesis  to  account  for  certain  results  in  his  study  of 
the  inheritance  of  color  in  the  aleurone  cells,  where  there  ap- 
peared to  be  a  dominance  of  the  maternal  condition.  Although 
East  and  Hayes  (1911)  were  able  to  show  that  Correns'  assump- 
tion was  unnecessary  in  the  case  of  aleurone  color,  the  aberrant 
ratios  obtained  being  due  to  the  interaction  of  several  factors, 
it  does  appear  to  fit  the  facts  in  the  crosses  just  described. 

A  cross  between  a  yellow  corneous  race  and  a  white  floury 
race  would  show  the  correct  explanation  of  the  results  of  the 
floury-flint  cross,  for  if  in  Fo  the  ratio  of  yellow  to  white  was 
3   to   1,   and   of   corneous  to   floury,   1   to   1,   it   would   then  be 


INHERITANCE    IN    MAIZE.  13 

established  that  there  was  a  fusion  of  the  female  polar  nuclei 
with  a  male  generative  cell.  Emerson  suggested  that  the 
same  test  could  be  made  by  pollinating  ears  which  were  expect- 
ed to  give  a  1  to  1  ratio  with  pollen  from  a  yellow  corneous  flint. 
At  the  time  this  test  was  to  be  made  no  seeds  of  the  immediate 
cross  between  the  corneous  and  floury  races  were  available,  but 
a  number  of  seeds  of  hybrid  ears  (10  x  5)-8C-8S-6  were  planted 
and  the  resulting  plants  crossed  with  pollen  from  a  corneous 
yellow  flint  known  to  breed  true.  Four  ears  were  obtained  of 
a  cross  between  (10  x  5)-8C-8S-6C  (the  corneous  seeds)  and 
the  yellow  flint.  They  proved  to  be  yellow  corneous  flints.  Of 
the  naturally  pollinated  ears  obtained  from  (10  x  o)-8C-8S-6C, 
13  were  pure  corneous  flints  and  18  hybrids.  Five  ears  of 
(10  X  5)-8C-SS-(3S  (the  floury  seeds)  were  also  pollinated  with 
pollen  from  the  yellow  corneous  race.  All  five  ears  were  yellow 
and  four  were  yellow  floury  ears.  One  ear  was  a  definite  hy- 
brid, however,  and  gave  a  ratio  of  55  floury  seeds  to  59  cor- 
neous seeds.  Of  the  open  field  ears  of  (10  x  5)-8C-8S-6S,  13 
were  pure  floury  and  14  hybrids. 

The  ear  which  had  all  yellozv  seeds  and  yet  showed  a  ratio 
of  55  floury  to  59  corneous,  seems  sufficient  evidence  for  con- 
cluding that  the  apparent  dominance  of  the  condition  of  the 
mother  is  due  to  the  fact  that  the  endosperm  is  produced  from 
a  union  between  two  female  polar  nuclei  and  one  male  cell. 
Thus  two  doses  of  a  flour  corn  factor  dominates  one  dose  of  the 
corneous  factor  and  vice  versa.  This  fact  has  an  important 
bearing  on  the  multiple  factor  hypothesis  for  interpreting  the  in- 
heritance of  quantitative  characters,  for  it  shozvs  that  a  series  of 
factors  may  have  cumulative  somatic  effects. 

Family  (10x6),  Flour  x  Dent. 

This  cross  was  made  in  1909  between  self-fertilized  strains 
of  Leaming  No.  6  and  floury  No.  10.  An  F^  generation  was 
grown  in  1910,  and  an  F.,  generation  from  the  seeds  of  ¥^  ear 
(10  x  6)-l  was  produced  in  1911.  There  was  no  appreciable 
effect  on  the  physical  condition  of  the  starch  in  the  seeds  of  No. 
10  due  to  the  pollen  of  No.  6.      On  the  F^  ears  the  seeds  were  in- 


14  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN     188. 

termediate  between  No.  10  and  No.  6  in  size,  and  were  rather 
uniformly  dented.  As  regards  the  appearance  of  the  starch  in 
the  seeds,  there  was  definite  segregation,  but  classification  was 
difficult  due  to  the  fact  that  all  seeds  contained  soft  starch  at 
the  cap  and  sides  and  were  dented.  The  seeds  of  the  self-fertiliz- 
ed F-L  and  F,  ears  were  all  examined  carefully  against  a  strong 
light,  however,  and  were  classified  as  accurately  as  possible.  The 
results  of  this  classification  are  given  in  Table  11.  Considerable 
variation  in  the  ratios  on  the  difi'erent  ears  is  exhibited,  but  as  a 
rule  there  is  an  indication  of  a  1  to  1  ratio. 

Although  this  seed  classification  may  not  have  been  as  ac- 
curate as  might  be  desired  owing  to  the  difficulties  involved,  the 
division  of  the  total  population  of  F.,  ears  into  corneous,  hybrid 
and  floury  types  as  shown  in  Table  12,  is  exact  and  serves  as  a 
complete  corroboration  of  the  theory.  Thirty-six  ears  were 
classed  as  pure  corneous,  eighty  as  hybrids  and  thirty-seven  as 
pure  floury.  This  is  certainly  a  close  approximation  of  a  1 :2  :1 
ratio. 

An  examination  of  the  F^  ears  showed  that  there  was  con- 
siderable range  of  variation  between  the  different  ears  which 
were  classed  as  corneous  or  floury  types.  There  was  a  little  va- 
riation among  the  seeds  of  the  same  ear,  but  this  was  not 
greater  than  could  be  explained  by  differences  in  development 
due  to  physiological  causes.  The  pure  corneous  or  pure  floury 
ears,  however,  diff'ered  from  each  other  by  a  considerable  amount, 
and  it  seemed  likely  that  some  of  this  variation  would  be  in- 
herited. Of  the  ears  of  Table  11,  (10  x  6)-l-13,  (10  x  6)-l-3 
and  (10  X  6)  1-4  bred  true  to  the  floury  type. 

The  corneous  seeds  of  ear  (10  x  6) -1-5  produced  13  hybrid 
and  17  pure  corneous  ears,  while  the  floury  seeds  yielded  19  pure 
floury  and  16  hybrid  ears.  Corneous  ear  (10  x  G) -1-5-2  was 
grown  the  following  year  and  produced  dented  ears  which  bore 
seeds  containing  a  fair  proportion  of  corneous  starch. 

Ears  (10  x  6)-l-6,  (10  x  6)-l-9,  (10  x  6)-l-12  and  (10  x  6) 
-1-14  of  Table  11  were  grown  in  1912.  All  produced  ears  hav- 
ing seeds  with  a  considerable  proportion  of  corneous  starch,  the 
progeny  of   No.    (10  x  6)-l-C)  and   No.    (10  x   6) -1-12   having 


INHERITANCE    IN    MAIZE. 


15 


about  the  same  proportion,  and  of  No.  (10  x  6j-l-9  and 
No.  (10  X  6) -1-14,  having  a  greater  proportion  of  corneous 
starch  than  the  dent  parent. 

TABLE  11. 

Record  of  Self- Fertilized.  Ears  of  F^  and  F,  Generation  of 

Cross  Between  No.  10  and  No.  6. 


Ear  Number 

Corneous  Seeds 

Floury  Seeds 

(10  X  6)- 

5 

104 

75 

(10  X  6) -2 

159 

226 

(10  X  6)- 

L-1 

123 

48 

'-2 

157 

152 

'-3a 

199 

• 

145 

'■-4a 

307 

250 

'-5 

342 

.    208 

'-6a 

149 

94 

'-7 

199 

182 

'-8 

124 

77 

'-9a 

259 

202 

'-10 

226 

196 

'-11 

212 

209 

'-12a 

182 

106 

'-13a 

107 

108 

'-14a 

42 

30 

'-15 

72 

85 

'-16 

hybrid   ear,   immature 

'-6 

considerable  corneous 

starch  in  all  seeds 

'-9 

all   seeds   very   cornec 

)US 

'-10 

some   varibility,    no    s 

eeds 

as   No.    10    (varia- 

tion  probably  du( 

;  to 

immaturity) 

'-11 

pure   corneous 

'-12 

pure  corneous 

'-14 

all  seeds  very  corneo 

us 

'-15 

pure  corneous 

'-3 

as  No.  10                    ) 
probably  as  No.  10   ) 

proved  pure 

'-4 

fi 

oury    in    1913 

'-16 

" 

'-17 

as   No.   10 

'-18 

" 

'-19 

" 

'-13 

11 

'-20 

" 

'-21 

Probably  as  No.   10 

'-22 

" 

'-23 

(( 

'-24 

(( 

Total  in  hybr 

id  ears 

2863 

2393 

16 


CONNECTICUT    EXPERIMENT    STATION,     BULLETIN     188. 

TABLE  12. 
F,  Ears  Obtained  From  Growing  Ear  (10  x  6)-l. 


Parent  Stock 

Pure 
corneous 

Hybrids 

Pure  Floury 

[Hand   pollinated   ears] 
Dark  yellow  seeds  of   (10  x  6)-l 
Light  yellow  seeds  of  ( 10  x  6)-l 
White  seeds  of    (10  x  6)-l 

7 
11 

7 
11 

16 
16 
24 
24 

.   12 

8 
8 
9 

Total     

36 

80 

37 

All  ears  obtained  from  ear  No.  (10  x  6) -1-9  selfed  had  small 
seeds  with  traces  of  dent.  On  some  ears  there  were  merely 
traces  of  dent,  but  other  ears  showed  the  dented  condition  in  all 
seeds.  Selections  were  made  to  determine  whether  these  varia- 
tions were  inherited.  In  1914  a  self -fertilized  ear  which  bore 
seeds  with  only  a  few  traces  of  dent  was  grown,  also  an  ear  with 
all  seed  dented.     The  progeny  of  these  ears  is  given  in  Table  13. 


TABLE  13. 
The  Progeny  of  E.vrs  No.  (10  x  6) -1-9-1   and  (10  x  6) -1-9-2. 


Progeny  Classes. 

Condition  of  Parent  Ear 

%  seeds 
dented 

%  seeds 
dented 

Few  seeds 
dented 

No  seeds 
dented 

Few  seeds   dented 
v4  seeds  dented 

9 
11 

12 

7 

14 
20 

1 
3 

These  results  show  that  little  progress  was  made  bv  the  se- 
lection. 

Of  the  self-fertilized  ears  obtained  from  ear  No.  (10  x  6) 
-1-14,  one  showed  no  trace  of  dent,  all  of  the  seeds  containing  a 
large  proportion  of  corneous  starch.  This  ear  was  grown  and 
compared  with  another  self-fertilized  ear  which  showed  traces  of 
dent  in  nearly  all  seeds.     The  results  are  given  in  Table  14. 


INHERITANCE   IN    MAIZE,    CONCLUSIONS.  li 

TABLE  U. 
The  Progenv  of  Ears  No.  (10  x  6) -1-14-1  and  (10  x  6) -1-14-2. 


Progeny  Classes 

Condition  of  Parent  Ear 

V2  Seeds  dented 

Few  seeds 
dented 

No  seeds  dented 

No  seeds  dented 
Half    seeds   dented 

5 

4 
11 

37 
19 

In  this  case  there  seems  to  be  some  effect  of  selection,  al- 
though the  number  of  individuals  grown  is  not  very  large. 

Conclusions. 

There  seems  to  be  a  close  agreement  between  the  results  of 
the  cross  between  10  and  6  and  those  reported  for  the  cross  l)e- 
tween  10  and  5.  It  was^  however,  more  difficult  to  classify  the 
seeds  in  the  (10  x  6)  cross  as  in  No.  6  corneous  starch  is  pro- 
duced only  on  the  sides  of  the  seed,  the  cap  and  the  immediate 
vicinity  of  the  embryo  being  filled  with  soft  starch. 

The  essential  dift'erence  between  No.  10  and  No.  6  in  type 
of  starch  produced  is  evidently  one  factor,  yet  since  different  F.. 
families  showed  variations  in  the  amount  of  corneous  starch  pro- 
duced, there  must  be  several  minor  factors  which  modify  its 
development.  There  is  good  evidence  that  at  least  some  of  these 
minor  factors  are  factors  which  have  a  direct  eff'ect  on  totally 
different  tissues.  For  example,  the  size  and  shape  of  the  seed 
which  is  at  least  partly  controlled  by  the  type  of  pericarp  (a 
maternal  character )  has  considerable  influence  upon  the  appear- 
ance of  the  starch.  To  put  the  matter  roughly,  in  plants  which 
fundamental!}'  have  the  same  zygotic  possibilities  as  regards  the 
type  of  starch  in  the  endosperm,  the  amount  of  soft  starch  ac- 
tually developed  is  directly  proportional  to  the  size  of  the  seed. 

Family  (10  x  64),  Floury  x  Rice  Pop  (Very  Corneous.) 

The  No.  10  parent  had  been  self-fertilized  for  three  years 
and  the  No.  64  parent  had  been  self-fertilized  for  two  years 
prior  to  1909  when  the  cross  was  made.  There  was  no  visibl^i 
eft'ect  of  the  pollen  of  No.  64  on  No.  10.     F^  ears  were  grown  in 


18 


CONNECTICUT    EXPERIMENT    STATION,    BULLETIN     188. 


1910,  but  in  no  case  was  there  a  clear  segregation  among  the 
seeds  like  that  occurring  in  the  F^  ears  of  crosses  (10  x  5)  and 
(10  X  6).  This  may  have  been  due  to  the  fact  that  the  ears  were 
somewhat  immature.  The  seeds  of  three  F^  ears  were  separated 
into  two  classes ;  first,  seeds  as  floury  as  No.  10 ;  second,  all  re- 
maining seeds.  These  partially  corneous  seeds  showed  a  range 
of  variation  from  very  corneous  seeds  to  those  which  contained 
only  a  little  more  corneous  matter  than  the  No.  10  flour  parent. 
The  result  of  this  classification  is  shown  in  Table  15. 


TABLE  15. 
F;^  Ears  of  Cross  Between  (10  x  61). 


Ear    Number 

Floury  Seeds 

Corneous    Seeds 

(10  X  64) -7 
(10  X  64)-10 
(10  X  64) -12 

93 

82 
168 

216 
349 
353 

Total     

343 

918 

The  seeds  of  (10  x  64) -7  and  (10  x  64) -10  were  planted  in 
1911.  Those  which  had  been  classed  as  of  the  floury  type  like 
No;  10  were  planted  as  (10  x  64) -7S  and  (10  x  64)-10S.  The 
remainder  of  the  seeds  of  the  same  ears  were  planted  as  (10  x  64) 
-TC  and  (10  x  64) -IOC  respectively.  The  results  obtained  from 
a  classification  of  the  progeny  of  these  ears  are  given  in  Table  16. 

TABLE  16. 

Ears  Obtained  From  Planting  (10  x  64)-7C  and  7S  and 

(10  X  64) -IOC  and  lOS. 


Progeny  Classes 

cU 

lU 

Parent    Type 

3 
O 

^   u 

'5  '•- 

edia 
eous 

1-   CU 

u 

3 

nterm 
Corn 

3    3 

^    C 

u 

PM 

'"' 

(10  X  64) -7S 

4 

15 

11 

6 

(10  X  64)-10S 

6 

13 

17 

2 

(10  X  64)-7C 

16 

7 

13 

(10  X  64)-10C 

1 

15 

6 

10 

INHERITANCE    IN    MAIZE.  19 

There  is  a  similarity  in  the  variabihty  of  the  populations  ob- 
tained from  the  floury  seeds  of  (TO  x  64) -TS  and  (10  x  64)-10S; 
the  progeny  of  the  corneous  seeds  of  (10  x  64) -10  and  (10  x  64) 
-7  also  show  about  the  same  percentage  of  ears  in  the  different 
classes. 

Two  self-fertilized  F^  ears  (10  x  64)-10S-5  and  (10  x  64) 
-lOC-4  were  classed  as  definite  hybrids.  The  corneous  seeds  of 
these  ears  gave  a  range  of  variation  from  purely  corneous  to 
definitely  hybrid  ears,  there  being  3.3  times  as  many  corneous, 
intermediate,  and  definitely  hybrid  ears,  as  there  were  pure  cor- 
neous ears.  The  floury  seeds  of  (10  x  64)-10S-5  and 
(10  X  64)-10C-4  produced  4.2  as  many  hybrid  and  intermediate 
ears  as  pure  floury  ears.  Thus  these  two  F^  ears  showed  as 
variable  a  progeny  in  Fg  as  had  been  found  in  Fo. 

Five  self-fertilized  Fg  ears  of  the  intermediate  floury  class 
from  the  progeny  of  (10  x  64)-10S  gave  a  total  population  of 
165  ears ;  of  which  19  approached  pure  corneous  but  contained  a 
larger  percentage  of  soft  starch  than  the  corneous  parent,  12  ap- 
proached the  floury  parent,  and  134  were  intermediate.  Many 
of  these  intermediate  ears  showed  some  variation  among  the  seeds, 
but  no  clear  segregation. 

F,  corneous  ears,  (10  x  64)-10C-9,  (10  x  64)-7C-9,  and 
(10  X  64)-7C-l  bred  true  for  the  corneous  habit  in  Fg.  (10  x  64) 
-lOC-9  was  grown  in  F^  and  again  bred  true. 

Pure  floury  ear  (10  x  64)-7S-13  bred  true  in  Fg  and  F^  for 
the  floury  habit. 

One  self-pollinated  intermediate  Fo  ear,  (10  x  64)-7C-2 
proved  to  be  a  hybrid  and  gave  in  Fg  15  corneous  ears,  32  definite- 
ly hybrid  ears  showing  clear  segregation,  and  18  intermediate  cor- 
neous ears  which  showed  some  variation.     This  is  a  1 :2  :1  ratio. 

Two  F^  ears  bred  from  the  intermediate  class,  (10  x  64) -7C- 
2-10  and  (10  x  64)-7C-2-l,  together  produced  14  ears  approach- 
ing pure  corneous,  68  intermediate  variable  ears  and  4  approach- 
ing pure  floury.  These  ears  are  probably  all  intermediates,  the 
variation  being  due  to  maturity  and  possibly  due  to  the  effect  of 
other  inherited  factors.  Of  3  other  F,  ears  classed  as  inter- 
mediate, 2  gave  intermediate  progeny  and  1  proved  to  be  a  definite 
hybrid.  Self-pollinated  ears  of  selections  (10  x  64)-7S-l  and 
(10  x  64)-7S-7  from  the  intermediate  class  were  grown  the  fol- 
lowing year.     These  results  are  given  in  Table  17. 


20 


CONNECTICUT    EXPERIMENT     STATION,     BULLETIN     188. 


TABLE  17'. 

Progeny  of  Ears  No.  (10  x  64)-7S-l  and  (10  x  64)-7S-7 

Which  Were  Classed  As  Intermediate  Variable 

Ears. 


Parent  type 

Classification  of  Progeny 

Ear  No. 

c 

s  I 

.5    P 

o    o 

< 

(10  X  64)-7S-l-3 

(10  X  64)-7S-l-6 

(10  X  64)-7S-7-10 

■'                     -3 

-4 

-S 

Most  corneous  ear 

"     floury  ear 
Intermediate  ear 

2 
3 

3 

35 
40 
35 
48 
47 
t46 

1 

I  Of  this  population.  25  open  field  ears  were  very  variable  and 
showed  definite  segregation.  The  self-fertilized  ears  were  comparatively 
uniform. 


The  data  in  Table  IT  show  that  intermediate  \ariable  ears 
tend  to  give  intermediate  variable  progeny.  The  ears  did  not  all 
become  thoroughly  mature,  and  this  may  be  the  explanation  of 
their  variable  endosperms.  There  is  also  the  possibility  that 
other  heterozygous  factors  may  have  influenced  development  in 
such  a  way  as  to  produce  variation.      (East  &  Hayes  1911). 

Eg  ear  (10  x  64)-10C-l-6  produced  intermediate  and  corneous 
seeds  in  a  ratio  approaching  1:1.  The  corneous  seeds  of  this  ear 
gave  a  progeny  of  28  purely  corneous  and  2-1  definitely  hybrid 
ears,  while  the  intermediate  seeds  gave  a  progeny  of  2  corneoits 
cars,  17  definite  hybrids  and  23  intermediate  variable  ears.  This 
is  a  close  approximation  of  a  1 :2  :1  ratio.  That  only  1  factor  de- 
termined whether  corneous  or  intermediate  seeds  were  to  be  pro- 
duced in  this  ear  is  further  indicated  by  the  separation  of  seeds 
from  five  self-pollinated  ears  which  were  classed  as  definite 
hybrids.  The  results  are  given  in  Table  18.  The  total  number 
of  corneous  seeds  in  these  five  ears  were  514  and  of  intermediate 
seeds  491.     This  clearly  approaches  a  1  to  1  ratio. 


INHERITANCE    IN    MAIZE.    SUMMARY. 


21 


TABLE    IS. 

Classification  of  Seeds  of  Hybrid  Ears  Obtained  From 

Planting  Intermediate  and  Corneous  Seeds  of  Ear 

(10  X  64)-10C-l-6. 


Ear  Number 

Corneous   Seeds 

Intermediate    Seeds 

(10  X  64;-lCC-l-6l-2 
-9 
-8 

(10  X  14)-10C-l-6C-8 
-10 

101 

78 

80 

135 

120 

84 

92 

67 
124 
124  • 

Total  in  hybrid  ears 

514 

491 

Summary  and  Interpretation  of  Results. 

The  pollen  of  No.  64  pop  apparently  had  no  effect  on  the 
character  of  the  endosperm  of  No.  10  flour.  This  is  in  agree- 
ment with  the  results  of  the  crosses  (10  x  5)  and  (10  x  6).  The 
Fj  ears  showed  the  results  of  segregation,  although  in  this  case 
there  was  a  range  of  variation  from  the  floury  to  the  corneous 
type.  Seeds  of  this  F^  generation  (Fo  seeds)  produced  a  popu- 
lation of  ears  ranging  from  the  pure  corneous  to  the  pure  floury 
type. 

One  uniformly  floury  ear  bred  true  in  Eg  and  F^^  for  the 
floury  habit ;  three  ears  with  purely  corneous  seeds  also  bred  true. 

Two  F,  ears  (10  x  64)-10S-5  and  (TO  x  64)-10C-4  gave  as 
variable  an  Eg  progeny  as  had  been  found  in  E,.  The  ratio  in  this 
case  was  approximately  1  pure  corneous  ear  to  6.2  intermediates 
and  definite  hybrids  to  0.8  pure  floury  ears. 

Other  Fo  ears  gave  a  1 :2  :1  ratio  in  Eg  as  was  the  case  in  the 
(10  X  5)  and  (10  x  6)  crosses.  An  example  of  such  a  ratio  is 
that  obtained  from  Fo  ear  (10  x  64)-7C-2,  which  produced  15 
corneous  ears,  32  definitely  hybrid  ears  and  18  intermediate  ears. 

Several  self-fertilized  intermediate  F2  ears  bred  comparative- 
ly uniformly,  giving  a  progenv  which  contained  more  corneous 
starch  than  the  No.  10  parent  but  less  than  the  No.  64  parent. 
Thus  intermediate  ear  (10  x  64)-7S-l  produced  41  ears  of  the 
intermediate  type  none  being  either  purely  corneous,  definitely 
hybrids,  or  clearly  floury.  A  self-fertilized  ear  (10  x  64)-7S-l-2 
which  contained  more  corneous  starch  than  other  self-fertilized 


22  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN     188. 

ears,  yielded  a  progeny  of  35  variable  intermediate  ears  and  2 
ears  approaching  the  corneous  condition  although  they  were  not 
truly  corneous  ears  like  No.  Qi.  Self-fertilized  ear  (10  x  64)-7S- 
1-6  which  approached  the  floury  type,  produced  10  intermediate 
variable  ears  and  1  ear  with  somewhat  more  floury  matter,  though 
it  did  not  compare  with  No.  10.  Thus  in  a  total  of  119  ears  from 
this  intermediate  line  (10  x  61)-7S-1  there  were  no  pure  cor- 
neous, pure  floury  or  definitely  hybrid  ears.  This  variation  may 
largely  be  due  to  differences  in  the  maturity  of  the  seeds  and 
ears,  as  the  amount  of  corneous  starch  is  directly  dependent  on 
the  maturity  of  the  seeds,  although  of  course  the  hereditary  con- 
stitution determines  the  amount  which  can  be  produced  under 
favorable  conditions,  but  there  is  also  considerable  likelihood  that 
what  one  may  call  minor  inherited  factors  modify  the  expression 
of  the  character.  Whether  more  than  one  major  factor  affecting 
the  endosperm  is  involved  is  still  a  question.  The  ratio  obtained 
among  the  progeny  of  ears  (10  x  61:)-10S-5  and  (10  x  61)-10C-4, 
the  facts  that  certain  F2  ears  produced  an  Fg  progeny  similar  to 
the  10  x  5  cross,  and  that  others  bred  approximately  true  to  the 
intermediate,  the  pure  floury,  or  the  pure  corneous  types  might 
seem  to  indicate  two  such  factors,  but  analysis  is  so  difficult  that 
this  is  only  a  reasonable  guess,  as  will  be  shown  by  a  considera- 
tion of  all  of  the  facts. 

The  following  conclusions  we  hold  to  be  justified  by  the 
data  at  hand. 

1.  The  factors  directly  responsible  for  the  dift'erences  in  the 
physical  condition  of  the  starch  exhibited  by  the  so-called  starchy 
sub-species  of  maize,  the  flour,  dent,  flint  and  pop  corns  are  as 
truly  endospermal  in  their  inheritance  as  endosperm  color  char- 
acters. They  partake  of  the  nature  of  the  embryo  and  not  of  the 
plant  on  which  they  are  borne. 

2.  These  characters  appear  superficially  to  be  maternal  for 
the  following  reasons.  The  endosperm  nuclei  are  triploid  due 
to  the  fusion  of  two  nuclei  from  the  female  gametophyte  with 
one  nucleus  from  the  male  gametophyte.  In  the  characters  under 
discussion,  the  presence  of  two  factors  always  dominates  the 
presence  of  one  factor.  Thus  corneous  female  (CC)  x  floury 
male  (F)  is  phenotypically  corneous,  while  floury  female  (FF)  x 
corneous  male   (C)   is  phenotypically  floury.     These  characters. 


INHERITANCE    IN    MAIZE.  23 

therefore,  appear  to  be  inherited  in  a  different  manner  from 
endosperm  colors  where  the  presence  of  one  color  factor  is  suf- 
ficient to  cause  perfect  development  of  color.  This  is  the  first 
proof  of  a  cumulative  somatic  effect  of  factors. 

3.  From  the  fact  that  in  these  crosses,  as  well  as  in  num- 
erous others  involving  the  same  subspecies  of  maize  that  we  have 
examined,  the  F,  reproduces  the  grandparental  and  no  types  more 
extreme  than  the  grandparental  types  (with  possibly  a  rare  ex- 
ception), it  follows  that  a  large  series  of  multiple  allelomorphs 
affecting  the  starchy  condition  of  the  endosperm  exists. 

4.  From  the  facts  (a)  that  where  no  complications  such  as 
dift'erences  in  shape  and  size  of  seed  exist  (viz.  cross  10  x  5) 
segregation  is  simple  and  definite,  (b)  that  where  such  differences 
in  shape  and  size  of  seed  do  exist  segregation  occurs  but  is  diffi- 
cult to  demonstrate  clearly  until  these  complications  have  been 
eliminated,  it  follows  that  although  only  the  presence  of  factors 
in  the  endosperm  affect  these  characters  directly,  the  maternal 
zygotic  constitution  has  an  indirect  effect.  This  effect  is  roughly 
a  direct  correlation  of  size  of  seed  with  floury  condition  of  the 
endosperm. 

Havmg  these  facts  m  mmd,  let  us  see  what  difficulties  ob- 
struct analysis  if  it  be  assumed  that  two  factor  differences  may 
differentiate  the  endosperms  of  certain  maize  varieties  in  respect 
to  starch  as  seemed  possible  in  the  case  of  cross  (10  x  64). 

The  simplest  assumption  would  be  that  each  of  these  factors 
has  a  similar  eff'ect,  and  when  one  sees  the  difficulties  thus  in- 
volved, and  considers  that  such  a  simple  assumption  is  less  prob- 
able than  one  in  which  each  factor  has  a  different  effect,  it  is 
clear  why  we  do  not  wish  to  assert  dogmatically  that  two  such 
factors  are  involved  in  the  cross  between  the  flour  and  the  pop- 
corn. 

Let  the  flour  corn  be  AABB  and  the  pop  corn  aabb,  it  being 
understood  that  the  phenomenon  of  dominance  is  in  this  case 
wholly  a  quantitative  reaction.  The  Fj  generation  in  the  cross 
and  its  reciprocal  would  be 

AAa  BBb 

and 
aaA  bbB 


24  CONNECTICUT    EXPERIMENT    STATION,     BULLETIN     188. 

In  each  case,  the  predominant  influence  of  the  mother  would  Ije 
such  that  any  effect  of  the  father  would  scarcely  be  noticeable. 
Four  types  of  gametes  would  be  formed  in  the  F^  generation  as 
usual,  AB,  Ab,  aB  and  ab, — but  the  appearance  and  breeding 
qualities  of  the  zygotes  formed  would  be  peculiar,  as  is  shown  in 
the  following  table,  due  to  the  fact  that  the  "gametes"  of  the 
embryo  sac  are  the  fusion  cells  AABB,  AAbb,  aaBB  and  aabb. 

1  AAABBB  1 

1  AAABBb  I        ,  ,.,     ,        ,  ,.^ 

1  AAaBBB  Appear  alike  breed  ditterently 

1  AAaBBb  j 

1  AAAbbB  1 

1  AAAbbb  [       .  ...     . 

1    A.AabbB  Appear  alike  breed  ditterently 


1  AAabbb  J 

1 

y      Appear  alike  breed  differently 


1  aaABBB  1 

1  aaABBb 

1  aaaBBB 

1  aaaBBb  J 


1  aaAbbB  1 

1  aaAbbb  ,       Appear  alike  breed  differently 

1  aaabbB  I  "  • 

1  aaabbb  J 

The  grandparental  types  haye  appeared  of  course  and  will 
breed  true,  but  other  indiyiduals  will  look  like  the  grandparents 
though  they  will  breed  differently  and  will  ultimately  giye  the 
whole  series  if  crossed  together.  Other  complications  will  occur 
to  any  one  who  takes  the  trouble  to  study  the  table. 

Family  (65  x  64),  White  Pearl  Pop  x  White  Rice  Pop. 

In  1910  a  cross  was  made,  between  white  rice  pop  No.  64  and 
pearl  pop  No.  65  for  the  dual  purpose  of  determining  the  probable 
yalue  of  such  a  cross  for  the  commercial  production  of  first  gen- 
eration hybrid  pop  corn,  and  to  study  the  inheritance  of  the 
pointed  seed  characteristic  of  the  rice  pop  corns. 

The  F-^  plants  were  considerably  more  vigorous  than  either 
parent.  The  seeds  produced  approached  the  length  of  those  of 
the  longer  type,  the  white  rice  pop,  and  the  width  of  those  of  the 


INHERITANCE    IN    MAIZE.  ',i'0 

broader  parent,  the  pearl  pop.  Thus  the  F.  seeds  (those  borne  on 
F^  plants)  were  considerably  larger  than  those  of  either  parent, 
and  since  the  pericarp  was  weaker  rather  than  stronger  than  that 
of  the  pure  tjqies,  the}^  did  not  pop  as  well. 

TABLE  19. 

Inheritance  of  Seed  Shape  in  a  Cross  Between  White  Rice 
Pop  No.  64  and  Pearl  Pop  No.  65. 


- 

Parent 
Type 

Condition   of   Progeny 

Ratio  of  Pointed 
ears  to  intermedi- 
ate and  non  point 

Ear    Xumber 

147 

6 
5 
9 

4 

Inter- 
mediate 
Point 

Non 
Point 

64-4 

65-8 

(65  X  64)    Fi 

(65  X   64) -1  F. 
"     -3  " 

-5 
•'     -6  '■ 
"     -1-13  Fo 

Pure  pt. 

Non  pt. 

Int.  pt. 

Int.  or  non 
pt. 

132 
64 
•49 
55 
58 

*21 

200 

1 
5 

3 

2 

1:10.8 
1:10.8 
1 :6.5 
1:15 

*  Possibly  non-point  as  the  point  was  scarcely  perceptible. 


The  data  on  the  cross  are  given  in  Table  19.  The  F^^  gen- 
eration was  of  intermediate  habit, — there  being  some  projection 
of  the  seeds  at  the  point  of  attachment  of  the  silk.  Four  selfed 
F-L  ears  furnished  F^  generations.  The  progen}^  of  these  ears  was 
variable,  the  seeds  of  some  ears  being  as  completely  pointed  as 
the  white  rice  pop  parent,  the  seeds  of  others  non-pointed  like 
the  pearl  pop  parent,  while  the  greater  number  were  of  various 
intermediate  types.  Of  a  total  progeny  of  263  individuals,  24 
ears  were  classed  as  pure  pointed  like  the  white  rice  parent. 
This  is  an  indication  of  a  15  :1  ratio,  although  one  can  not  be  cer- 
tain that  the  classification  was  correct  because  these  ears  were 
not  selfed  and  could  not  be  tested  by  the  type  of  progeny  produc- 
ed. A  number  of  F^  ears  were  self-pollinated,  but  none  happened 
to  be  obtained  which  could  be  classed  as  typically  pointed.     One 


26  CONNECTICUT    EXPERIMENT    STATION,     BULLETIN     188. 

ear  having  seeds  but  slightly  pointed  (possibly  non-pointed)  was 
grown  in  F,.  The  twenty-one  ears  produced  were  like  the  parent 
ear,  showing  only  slight  projections  on  the  seeds  at  the  tip  of  the 
ear. 

The  difference  between  the  pointed  seed  characteristic  of  the 
white  rice  pop  corn  and  the  normal  shape  of  seed  typical  of  other 
varieties  can  not  be  explained  by  a  single  factor.  If,  however,  we 
assume  that  there  is  a  difference  in  two  factors,  that  each  factor 
is  allelomorphic  to  its  own  absence  and  is  inherited  independently 
of  the  other,  that  both  are  necessary  for  the  production  of  the 
pure  pointed  condition,  and  that  either  of  them  alone  may  pro- 
duce a  tendency  to  a  pointed  condition  (intermediate  point),  the 
data  accord  fairly  well  with  the  theory.  But  since  on  this  hypo- 
thesis it  is  assumed  that  a  factor  in  the  heterozygous  condition, 
produces  only  half  as  great  an  effect  as  when  homoz3'gous,  one 
can  appreciate  the  difficulty  of  classifying  the  ears  correctly  by  in- 
spection, and  since  classification  must  be  exact  to  prove  such  a 
case  merely  by  the  ratios  obtained  it  must  be  admitted  that  our 
evidence  is  open  to  some  criticism.  On  the  other  hand,  we  be- 
lieve that  the  facts  are  clear  enough  to  make  them  of  some  value 
in  practical  plant  breeding,  and  we  do  not  believe  that  the  case  is 
sufficiently  important  to  make  it  worth  while  overcoming  the 
difficulties  that  stand  in  the  way  of  a  more  acceptable  proof. 
Furthermore,  the  data  on  the  next  cross  appear  to  corroborate  our 
earlier  facts. 


Family  (64  x  6),  White  Rice  Pop  x  Leaming  Dent. 

This  cross  was  made  in  1909  between  self-bred  Leaming  and 
white  rice  pop  strains.  The  purpose  of  this  cross  was  a  further 
study  of  the  mode  of  inheritance  of  quantitative  differences  in 
seed  size,  of  the  proportion  of  corneous  to  soft  starch,  and  of  the 
pointed  habit  of  the  white  rice  pop. 

The  results  on  inheritance  of  seed  shape  are  given  in  Table 
20.  These  results  again  indicate  that  two  factors  are  involved. 
Furthermore,  examination  of  Table  20  and  Table  21,  shows  that 
the  pointed  character  is  inherited  independently  of  the  position  of 
starch  in  the  seeds. 


INHERITANCE    IN    MAIZE. 


TABLE  20. 

Inheritance  of  Seed  Shape  in  a  Cross  Between  No.  6 
Leaming  Dent  and  No.  64  White  Rice  Pop. 


Parent 
Type 

Condition   of   Progem' 

Ear    Number 

Pure 

Inter- 

Non 

Point 

mediate 
Point 

Point  " 

64-4                      Pi 

Pure   pt. 

147 

6-3-4                     Pi 

Dent  non  pt. 

107 

6  X  64                  Fi 

112 

(6  X  64) -4         F. 

Int.  pt. 

47 

65 

20 

-6         F2 

" 

35 

44 

17 

-6-6     F3 

Pure  pt. 

26 

-6-3     F3 

"■ 

21 

2 

-4-8     F3 

Pure  (?)  pt. 

44 

20 

-4-9     F3 

41 

11 

-6-4     F3 

Int.  pt. 

4 

44 

1 

-4-6     F3 

" 

13 

31 

-4-4     F3 

" 

13 

,    37 

2 

-6-5     F3 

Non  pt. 

4   (?) 

53 

4 

-6-7     F3 

" 

3 

34 

-4-3     F3 

" 

2 

41 

17 

-4-7     F3 

" 

11 

45 

7 

-4-10  Fa 

" 

52 

13 

-4-5      F3 

" 

6 

37 

3 

(6  X  64) -6-6-4  F4 

Pure   pt. 

35 

-6-6-1  " 

Pure  or  int.  pt.  (  ?) 

27a 

-4-8-8  " 

Pure  pt. 

61b 

K?) 

-6-3-6  " 

" 

43 

-6-5-4  " 

Int.  pt. 

K?) 

38 

5 

-6-5-3   " 

K?) 

35 

11 

-6-7-8  " 

26 

11 

-4-8-3  " 

16 

40 

-4-3-7  " 

5 

72 

-4-10-5  F4 

47 

22 

-4-10-3  F4 

Non  or  int. 

48 

17 

-4-3-5  F4 

Non 

60 

a — 4  ears  with  points  not  as  strongly  developed  as  the  remaining  ears, 
b — 1  ear  with  points  not  as  strongly  developed  as  the  remaining  ears. 

The  F^  generation  was  intermediate  as  regards  the  pointed 
Condition,  and  there  was  segregation  into  pointed,  non-pointed  and 
intermediate  ears  in  F.,.  Thirteen  self-polHnated  F.,  ears  were 
grown  in  F.:,.  Of  these,  the  following  F.,  ears  were  classed  as 
pure  pointed,  (6  x  Gi)-6-6,  (6  x  64)-6-3,  (6  x  64)-4-8,  (6  x  64) 
-4-9.  Two  of  these  ears,  (6  x  64) -6-6  and  (6  x  64) -6-3,  bred 
true  in  F^,  while  (6  x  64)-4-8  and  (6  x  64)-4-9  showed  segrega- 


28  CONNECTICUT    EXPERIMENT    STATION,     BULLETIN     188. 

tion  in  F.,  with  a  total  of  85  pointed  and  31  intermediate  pointed 
ears.  Tavo  self-fertilized  ears,  (6  x  6-1 J -4-8-8  and  (6  x  61) 
-4-8-3,  were  grown  in  1914.  One  proved  to  be  a  pure  pointed  ear 
and  the  other  again  gave  pure  pointed  and  intermediate  pointed 
seeds.  These  results  might  have  been  obtained  if  ear  (6  x  64) 
-4-8  were  homozygous  for  one  factor  for  point  and  heterozygous 
for  a  second  factor. 

Three  self-fertilized  F2  ears  of  the  intermediate  class  showed 
a  range  of  variation  in  F3  from  pure  pointed  to  non-pointed  ears. 
Six  F2  ears  classed  as  non-pointed  Avere  proved  to  have  been 
hybrids  by  the  F3  results.  One  of  these,  (6  x  64)-4-T,  produced 
52  intermediate  and  13  non-pointed  ears.  As  no  typically  pointed 
ears  were  obtained  it  seems  fair  to  conclude  that  the  parent  ear 
(6  X  64) -4-7  was  heterozA^gous  for  1  factor  for  pointed  seeds. 

Tavo  self -fertilized  F3  ears  of  line  (6  x  64) -6-6  Avhich  bred 
true  for  the  pointed  habit  in  F3  Avere  groAvn  in  F^.  Ear  (  6  x  64) 
-6-6-4  gave  a  progeny  of  35  ears,  all  of  Avhich  Avere  pure  pointed : 
while  (6  x  64) -6-6-1  had  a  progeny  of  33  pure  pointed  ears  and  4 
Avith  points  more  strongty  developed  than  the  intermediate  class, 
but  not  so  strongly  developed  as  the  23  pure  pointed  ears.  This 
mav  be  a  physiological  A'ariation  or  it  may  possibly  l)e  due  to 
chance  pollination.  As  these  four  were  open  field  ears,  it  is  im- 
possible to  determine  the  matter  by  further  breeding. 

The  results  are  an  excellent  illustration  of  the  old  A'ilmorin 
Isolation  Principle, — in  modern  times  the  genotype  hypothesis. — 
for  they  shoAv  that  the  only  sure  method  to  determine  the  breeding 
value  of  an  ear  is  to  grow  and  examine  its  progeny.  A  part  of 
the  pure  pointed  class  gave  a  pure  pointed  progeny ;  other  ears 
proved  to  be  hybrids.  There  Avas  also  considerable  difference  in 
the  progeny  of  different  intermediate  ears ;  some  being  apparently 
homozygous  for  one  factor  for  point  and  heterozygous  for 
another,  Avhile  others  appeared  to  be  heterozygous  for  a  single 
factor. 

These  results,  as  did  those  in  the  case  of  the  (65  x  64)  cross, 
indicate  that  two  factors  are  involved  in  the  production  of  strong- 
ly pointed  maize  seeds. 

Table  21  gives  the  results  of  a  study  of  the  dented  condi- 
tion and  the  proportion  of  corneous  to  floury  starch  in  the  same 


INHERITANCE    IN    MAIZE. 


2'.) 


cross.  The  white  rice  pop  parent  contains  only  a  small  amount 
of  floury  starch,  while  the  dent  variety  has  corneous  starch  at  the 
sides  of  the  seed  and  floury  starch  at  the  cap  and  next  the  em- 
bryo. There  was  no  effect  on  the  development  of  the  amount  of 
corneous  starch  in  No.  6  dent  due  to  the  pollen  from  No.  64  pop. 
The  F^  generation  cross  produced  ears  with  intermediate  sized 
seeds.     These  ears  would  have  to  be  classed  as  dents. 

TABLE  21. 

Inheritance  of  Dented  Habit  and  Proportion  of  Corneous 
TO  Floury  Starch. 


Parent    Type 

Condition 

of   Progeny 

Ear    Number 

-w 

_^ 

T3 

0 

■*>-S 

-■2 

m"^ 

T3 

f; 

«  ?^ 

M-i     ^ 

A  a 

£ 

^l 

5  S 

fe-d 

i^ 

64-4 

pop,    non-dent 

107 

6-3-4 

dent 

147 

6  X  64    Fi 

112 

(6  X  64) -4  Fo 

nearly  pure   dent 

15 

27 

27 

20 

3 

-6  " 

"            '•         " 

38 

34 

21 

8 

-4-4  F3 

pure  dent 

29 

1 

15 

5 

1 

-4-5  " 

"         " 

1 

11 

24 

6 

-4-8  " 

"         " 

39 

9 

;       -6-6  " 

"         " 

24 

2 

-6-5   " 

"         " 

25 

19 

13 

4 

-6-7  " 

nearly  pure   dent 

3 

11 

15 

5 

2 

-6-4  " 

"            "         " 

2 

2 

35 

8 

2 

-4-7  " 

half   seeds   dented 

14 

24 

5 

3 

-4-9  " 

"         "            " 

30 

a 

8 

2 

-4-6  " 

few  seeds  slightly  dented 

12 

7 

11 

14 

-6-3   " 

"        "           "             " 

2 

2 

35 

8 

2 

'       ■     -4-10" 

non-dented 

17 

48 

-4-3   " 

"         " 

26 

34 

-6-3-6  F4 

pure  dent 

2 

5 

12 

21 

2 

-6-5-3  " 

"         " 

32 

1 

4 

-6-5-4  " 

"         " 

6 

23 

12 

3 

-6-6-1  " 

"         " 

2 

3 

9 

12 

1 

-6-6-4  " 

"         " 

15 

14 

4 

2 

-6-7-8  " 

half   seeds   dent 

1 

4 

9 

23 

-4-8-8  " 

half  seeds  slightly  dent 

6 

21 

16 

IS 

' 

-4-8-3  " 

seeds   slightly   dent 

4 

28 

12 

13 

-4-3-7  " 

few    seeds    dent 

1 

8 

29 

40 

-4-3-5  " 

no  seeds  dent 

5 

44 

-4-10-5  F4 

few  traces  of   dent 

5 

63 

-4-10-3   " 

non-dent 

67 

30  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN     188. 

Two  Fi  ears  (6  x  64) -4  and  (6  x  64) -6  were  grown  in  F^. 
Both  populations  showed  a  wide  range  of  variation.  The  ears 
were  classed  as  pure  dent,  nearly  pure  dent,  half  seeds  dent,  few 
seeds  dent  and  non-dent.  Ear  (6  x  64) -4  had  progeny  of  each 
class,  while  (6  x  64) -6  produced  progeny  in  all  classes  except  the 
non-dent  class.  Thirteen  F2  ears  were  grown  in  F,.  Two  non- 
dented  ears  gave  a  progeny  of  non-dented  ears  and  ears  with  a 
few  seeds  slightly  dented.  No  ears  bred  true  in  F3  or  F^  for  the 
pure  dented  condition,  although  some  selections  gave  a  progeny 
with  a  much  larger  proportion  of  dented  ears  than  others. 

Twelve  F3  ears  were  grown  in  F4.  Ear  (6  x  64) -6-5-3  pro- 
duced the  greater  proportion  of  its  progeny  in  the  pure  dent  class. 
Ear  (6  x  64) -4-10-3  bred  true  to  the  non-dented  character,  and 
the  corneous  non-pointed  condition.  Ear  (6  x  64) -6-5-3  bore 
seeds  which  approached  the  size  of  those  of  the  No.  6  Learning 
parent,  although  the  range  of  variation  was  somewhat  greater. 
Ear  (6  X  64) -4-8-3  gave  a  uniform  progeny  in  1914,  and  bred 
comparatively  true  to  the  seed  size  of  the  pop  parent. 

The  seeds  of  those  ears  which  were  classed  as  non-dents  and 
those  with  a  few  seeds  dented,  popped  perfectly  whe?n  tested. 
The  condition  of  the  other  families  is  shown  in  the  table. 


Summary  and  Interpretation  of  Results. 

The  data  from  these  two  crosses  indicate  strongly  that  two 
independently  inherited  factors  are  necessary  for  the  production 
of  a  strongly  pointed  seed.  The  rice  pop  point  can  be  transferred 
from  the  pop  parent  to  dented  seeds  by  crossing  and  selection ; 
the  inheritance  of  these  characters  being  entirely  independent  of 
each  other. 

A  study  of  the  proportionate  amount  of  corneous  and  floury 
starch  in  the  6  x  64  cross  shows  a  wide  variation  in  Fo.  One  ear 
(6  X  64) -4-10-3  bred  true  for  about  the  same  amount  of  corneous 
starch  in  F^  as  that  of  the  No.  64  parent.  Other  ears  were  again 
as  variable  as  F^,  while  still  others  showed  a  smaller  range  of 
variability.  It  is  impossible  to  state  how  many  factors  are  in- 
volved in  producing  these  somatic  difl:'erences,  but  it  is  a  fact  that 
the  parental  types  can  be  recovered  easily  and  will  breed  true. 


inheritance  in  maize,  conclusion.  31 

Conclusion. 

Since  a  summary  of  the  results  obtained  for  each  cross  has 
been  given  in  its  proper  place,  it  seems  unnecessary  to  repeat 
them  here.  If  the  reader  will  refer  to  them  he  will  find  an  ab- 
stract of  the  paper. 

Literature  Cited. 

CORRENS,  C. 

1901.  Bastarde  zwischen  Mai-srassen  niit  besonderer  Be- 
riicksichtigung  der  Xenien.  Bibliotheca  Botanica. 
53:1-161. 

EAST,  E.  M.  and  HAYES,  H.  K. 

1911.  Inheritance  in  Maize.  Connecticut  Expt.  Sta.  Bull. 
167:1-142. 

EMERSON,  R.  A.  and  EAST,  E.  M. 

1913.  The  Inheritance  of  Certain  Quantitative  .Characters 
in  Maize.     Nebraska  Station  Research  Bull.  3  :1-130. 

SHULL,  GEORGE  HARRISON. 

1914.  Duplicate  Genes  for  Capsule-form  in  Bursa  bursa- 
pastoris.  Zeitschrift  fiir  induktive  Abstammungs-und 
Vererbunffslehre  XII:  97-149. 


PLATE  I. 


No.  5,  corneous  flint  at  bottom,  No.  10  flour  at  top  and  Fi  at  left. 
The  two  lower  center  ears  show  the  result  of  planting  corneous  Fi 
seeds  and  the  two  upper  center  ears  show  the  result  of  planting 
floury  Fi  seed. 


PLATE  II. 


a.  No.  10  flour  at  left.  No.  G,  Learning  dent  at  right.  The  four  other  ears 
represent  the  Fs  generation  of  cross.  They  are  uniformly  very  corneous  with 
sHght  traces  of  dent.  The  seeds  are  smaller  than  those  of  either  parent  and 
of  uniform  size. 


h.     Average  ears  of  No.  65  pearl  pop  at  left,  No.  64  rice  pop  at  right  with 
average  Fi  in  center.     The  two  remaining  ears  represent  the  extremes  of  Fo. 


PLATE  III. 


a.  Xo.  G  Learning  dent  at  right,  No.  64,  rice  pop  at  left  and  immediate 
cross,  (6  X  64),  above.  The  two  central  ears  show  the  variation  in  seed  size 
and  condition  of  point  of  the  Fi  generation. 


b.     Fs  generation  of  cross   (6  x  64).     Note  the  segregation  of  characters. 


PLATE  1\' 


(6XfeV)-V-/0 


(6>C6V;-6-J" 


^U 


('GXfeV)-($-6 


Upper  row,  F3  generation  ears,  with  large  amount  of  corneous 
starch.  Some  ears  with  slight  trace  of  dent.  Middle  row,  average 
progeny  of  F2  ear  which  bore  good  sized  dented  seeds.  Lower  row, 
average  progeny  of  F2  ear  which  bore  intermediate  dented  seeds 
with  a  well-developed  point. 


PLATE  V. 


t4 


(644)-6-6-4 


6-64J-4-/0-J 


(6>^6i)'(,-S-3 


(M4M-^-^ 


Average  ears  of  parental  types  No.  6,  Learning  dent  and  No.  64,  white 
rice  pop  above.  The  ears  below  represent  the  variation  in  4  F4  families. 
(6  X  64) -6-6-4  bred  true  for  the  rice  point,  (6  x  64) -4-10-3  bred  true  for 
corneous,  non-dented  seeds,  (6  x  64) -4-8-8  is  a  small-seeded  selection  and 
(6  X  64) -6-5-3  is  a  large-seeded  selection.      (Photo  by  Walden.) 


PLATE  VI. 


O0UH)-7S-IZ 


Oox6V)-/OC-9 


Upper  row,  ¥s  generation  of  cross  between  Xo.  10  flour  and  Xo. 
64,  rice  pop,  which  bred  true  for  the  floury  habit. 

Middle  row,  F3  generation  of  same  cross  which  bore  seeds  of 
intermediate  t5'pe. 

Lower  row,  F3  generation  of  same  cross  which  bred  true  for  the 
corneous  habit. 


PLATE  VJ[. 


Qox(,^)-/OS'(, 


a.     Fs  generation  of  cross  between  No.  10  and  No.  64  which  bred  true  for 
the  seed  size  of  No.  10. 


b.     F.,  generation  of  cross  between  No.  10  and  No.  64  which  bred  true  for 
the  seed  size  of  No.  64.     The  corneous  seeds  popped  perfectly. 


^  ^  o  n 

^  O  0  y  n  7 


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